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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 831 · 40 sums
TalentJR

The method (Threes make cubes): Cube: n × n × n. Cube root: the number that, used three times, gives the cube. Units digits: 1→1, 2→8, 3→7, 4→4, 5→5, 6→6, 7→3, 8→2, 9→9, 0→0 — use them to guess cube roots. Make a perfect cube: break into primes; multiply by what completes each group of three (or divide by what is left over). A big cube of edge a cut into small cubes of edge b gives (a ÷ b)³ small cubes.

NameDateTime takenScore ___ / 40
  1. 1.Which of these is a perfect cube? (a) 789 (b) 729 (c) 776
  2. 2.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  3. 3.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  4. 4.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  5. 5.What is ∛1000? =
  6. 6.What is 6³? =
  7. 7.Which of these is a perfect cube? (a) 1331 (b) 1425 (c) 1414
  8. 8.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛2197? =
  10. 10.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 305 (b) 241 (c) 216
  12. 12.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  13. 13.What is 17³? =
  14. 14.Which of these is a perfect cube? (a) 3452 (b) 3375 (c) 3753
  15. 15.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  16. 16.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.Which of these is a perfect cube? (a) 402 (b) 343 (c) 457
  18. 18.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.What is 10³? =
  20. 20.Which of these is a perfect cube? (a) 35 (b) 34 (c) 27
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  23. 23.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  24. 24.What is 14³? =
  25. 25.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  27. 27.What is ∛9261? =
  28. 28.What is 5³? =
  29. 29.What is 16³? =
  30. 30.What is ∛6859? =
  31. 31.What is 20³? =
  32. 32.What is 9³? =
  33. 33.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  35. 35.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is 11³? =
  37. 37.What is ∛64? =
  38. 38.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  40. 40.Which of these is a perfect cube? (a) 1042 (b) 1000 (c) 1157

Answer key

  1. 729
  2. 2
  3. 25
  4. 2
  5. 10
  6. 216
  7. 1331
  8. 6
  9. 13
  10. 4
  11. 216
  12. 10
  13. 4913
  14. 3375
  15. 3
  16. 125
  17. 343
  18. 8
  19. 1000
  20. 27
  21. 216
  22. 20
  23. 4
  24. 2744
  25. 14
  26. 2
  27. 21
  28. 125
  29. 4096
  30. 19
  31. 8000
  32. 729
  33. 8
  34. 3
  35. 216
  36. 1331
  37. 4
  38. 25
  39. 25
  40. 1000

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